BACKGROUNDSelenium (Se) is an essential beneficial trace element for human and animals; taking an appropriate amount of selenium is an important sign to improve the quality of life. Eating selenium-rich agricultural products is an important way for humans to obtain and supplement selenium in low-Se regions. Investigating the content characteristics of soil selenium, delineating the distribution of selenium-enriched soil resources and identifying the influencing factors of soil selenium migration and enrichment can provide a sound basis for the efficient utilization of selenium-enriched soil resources and scientific development of selenium-enriched agricultural products.

OBJECTIVESTo reveal the content, distribution characteristics and influencing factors of selenium in soils from the study area.

METHODSSoil samples were collected from the western area of Muchuan County, Sichuan Province. AFS, ICP-MS and XRF were used to determine the elemental content (Se, Al₂O₃, TFe₂O₃, OrgC, Cd) and pH values. The content, distribution and influencing factors of soil selenium in the study area were evaluated using statistical and correlation analysis.

RESULTSThe results showed that: (1) The content of selenium in the study area ranged from 0.08 to 1.30mg/kg, with an average value of 0.39±0.15mg/kg. The selenium-rich land was 112km², accounting for 52% of the total area, of which the nuisanceless selenium-rich land was 35km². Soil Cd content was the main factor causing the great difference between selenium-enrich soil and nuisanceless selenium-rich soil. (2) The geological background was closely related to the soil selenium content, which was mainly controlled by carbonate rocks, sandstone and siltstone intercalated with carbonaceous strata. The source of soil selenium was stable. (3) The soil selenium content decreased with pH and ba value, meanwhile, they increased with TFe₂O₃ and S content. The effect of organic matter on soil selenium was significantly greater than TFe₂O₃, indicating that the adsorption capacity of TFe₂O₃ for selenium in this area was lower than organic matter.

CONCLUSIONSSelenium-enriched land resources are abundant in the study area. The content of soil selenium is affected by geological background and physical and chemical properties. It is suggested that local governments make full use of relevant resources to develop selenium-enriched agricultural products. At the same time, attention should be paid to the balanced fertilization of organic fertilizers. The collaborative analysis of factors affecting the migration and enrichment of selenium in the soil-crop system should be further strengthened.